Help idling to fast scared may go ka-boom!

Rights guys this going to be a long one

I replaced my vx 125 engine with a Vespa gts 125 engine.. I put my exhaust and carb on the Vespa gts engine, I couldn't fit the standard air box on so I bort a smaller air box ( not a sports one).. As I put pipes back on carb and so on I got muddle up and put the small water pipe on wrong and it had water coming through the air intake part of the carb " was quite funny to see tbh I thought you mug to myself " I tryed to start it and would firing up, any way I drained carb had water at first then petrol came threw and it fired up straight away.. But the engine is idling really fast and when I throttle it dies, I also noticed the bottom exhaust pipe was smoking not from manifold just smoking and got really hot I had engine running no longer than 20 seconds.. I'm thinking is it the new air filter? Or because iv got my vx 125 carb on the Vespa engine? Any ideas guys? Just want to get it running good and back on the road been messing around with it for too long now basically.. Thanks for your time and any advice you may have..

 

sounds like its running too rich, try taking the air filter off and see how it runs? on those carbs they have an enrichment pump so first 1/8th throttle tunr squirts petrol direct into the intake (a sort of boost) if its running too rich then this extra fuel boost will just flood it right out if you follow me?
also make sure to check your coolant system doesnt have any air.
the exhaust gets hot quickly on all bikes its just what they do, if its starts glowing then i would worry (that would be too lean)

 

but auto choke could also cause this, try running it for a few mins on idle and see if it clears up

 

Cheers mate, do you think it's not getting enough air then? Or two much?